How is estimated calving date / expected due date calculated?
Estimated calving date, sometimes referred to as expected due date, is calculated differently based on the type of breeding.
Also, a default gestation period of 285 days is used in calculations. However, this gestation period can be customized on a breed level from the Breeds list screen. To view/edit the Breeds List click on My Account > Breeds List.
Natural Service breedings
Estimated calving date is initially calculated by adding the gestation period to the breeding start date. While it’s not realistic to expect all cows to be bred on the first day of the breeding season, it is still better to know a cow is due a little early than to walk out in the pasture and see she has already calved.
If you pregnancy check your cows and specify a pregnancy check result of Pregnant and a Days/Months Pregnant is entered, the pregnancy check information will be used to update the estimated calving date to a more precise date.
Also, pregnancy check records with a result of “Recheck”, regardless of whether a time pregnant is entered, will not cause the estimated calving dates to be updated.
Artificial Insemination breedings
As with natural service breedings, the estimated calving date is calculated by adding the gestation period to the breeding date. However unlike natural service breedings, a pregnancy check result of Pregnant and a Days/Months Pregnant is entered will not cause the estimated calving date to change.
Embryo Transfer breedings
The estimated calving date is calculated by adding the gestation period of the recipient to the breeding date and then subtracting out 7 days to account for the time the embryo was in the donor. Pregnancy check results of Pregnant where Days/Months Pregnant is entered do not cause the estimated calving date to change.
Estimated calving date is not updated for AI and ET breedings because of the fact time pregnant is a "judgment" call by the pregnancy check technician and not an exact science.